1. Field of the Invention
A bath and process for reversal color development of high speed color cine film to produce color positives having reduced contrast at the dark end of the tone scale.
2. Description of the Prior Art
There currently are on the market films that are used for motion picture cameras and particularly for the taking of color motion pictures. One such film is a high speed color reversal cine film. Such a film, after processing, will yield high contrast images which are intended to be used for direct projection. The usual final use of such a film is to make color cine prints to be released for general public consumption, as to theaters or to television stations or for direct viewing through a telecine chain (air prints). When the prints released are duplicates of the original, the film used for the duplicates (prints) is a low contrast color reversal cine film. Even so, the high contrast of the original film is further increased by the duplication step.
A present day typical high speed color reversal cine film is an Eastman high speed VNF (Video News Film) 7250 (a speed of 400 tungsten and 250 daylight with an 85 conversion filter). Other typical high speed color cine VNF films are Eastman 5240 and 7240 (a speed of 125 tungsten and 80 daylight with an 85 conversion filter). These films are of relatively high contrast, designed for direct projection without duplication. A typical present day original reversal film is Eastman Kodak's Ektachrome commercial film 7252(a speed of 25 tungsten and 16 daylight with an 85 conversion filter). This is a low contrast original film not meant for direct projection but designed as a printing film, i.e., for duplication. The major disadvantage of this film is its unusually low camera speed.
The current practice for many filmic situations such as news gathering, cinema verite, documentaries, and location shots where electric power for supplemental lighting is unavailable, requires the use of a much higher camera speed than that provided by slow speed low contrast film and hence it has become mandatory to use the high speed VNF film for television news gathering, documentary filming, industrial filming and the like where the lighting is poor and/or the filmic situation is relatively uncontrollable. Where high speed cine film of the color reversal type is used for television news (in which time is of the essence) or where the film is to be later duplicated at a film processing laboratory, the problem of high contrast in the original creates considerable difficulties. Frequently the contrast, either that of the original or that of the duplicate produces unacceptable pictorial results. The problem is that the mid-scale and dark areas of the D log E curve are too "contrasty," resulting in an inability to distinguish between different shades of darkness. For example, if a dark skinned person is located in a heavily shadowed area, their face and background will blend and distinguishing features will be lost. The television industry refers to the problem as one of "dark tone compression," meaning that a given dark object is indistinguishable from an adjacent dark object. This is a direct result of a high contrast image effected by the harsh lighting conditions encountered in most news cine stories and the inability of the television broadcasting industry, with its presently available equipment, to reproduce for viewing the long tonal scale of a direct projection film.
In order to overcome this problem, the current practice of the television and certain segments of the movie industry with regard to film destined to be developed for documentaries, features or for news stories, where it is known that dark tone compression will be encountered, is to post flash the exposed but undeveloped images in which the aforementioned problem otherwise would arise. The pictorial effect of post flashing is to reduce image contrast. When practiced, it actinically reduces the high contrast inherent in a high speed color reversal camera film. However, post flashing is a very difficult procedure. It must be performed on a carefully controlled motion picture printer by a highly trained technician, and preferably is done to an exposed image only after the effects of post flashing have been tested on a raw stock of a similar origin, for example, the same lot number of emulsion.
The difficulties associated with post flashing are many. It can and frequently does result in a scratching of the emulsion. The flashed image may be uneven due to mechanical problems. There has been a lack of repeatability on a day-to-day basis. The trade has no set standards for post flashing; the judgment of the operator must be relied on totally. Post flashing preferably is not used for television news because in addition to all of its other drawbacks, the time delay in sending a film--an undeveloped film--to a motion picture laboratory for post flashing and having it returned is intolerable. Television news is cursed with the need for immediacy. The television news media does not want to be subjected to the time delay necessary for a motion picture laboratory to treat film. It does not wish to subject itself to the uncontrollable vagaries of a third party film processor. It wishes rigorously to control the time needed for processing by having the processing performed by its own personnel on its own premises and these personnel are not trained sufficiently to do post flashing. Furthermore, post flashing adds an additional cost to the processing of VNF and if performed by the television studio technicians would necessitate the addition of considerable extra equipment.